Grizzled former Marine sniper Bob Lee Swagger tackles the granddaddy of all conspiracy theories — the 1963 Kennedy assassination — in his latest adventure. Hunter’s reliance on film references and clichés has left Swagger a rather dull boy — comparing him to Clint Eastwood and John Wayne passes for detail — but the author’s obsessive attention to the events of Nov. 22 yields a stunningly plausible theory that will have readers holding the book in one hand and Googling satellite photos of Dealey Plaza and the Texas School Book Depository with the other. Fans of the Swagger series will revel in the ghosts from 1992’s Point of Impact that reemerge in Dallas, plus a rogue CIA agent who brings us face-to-face with Lee Harvey Oswald. Swagger keeps complaining he’s ”too old for this s—,” but if this is his last ride, he goes out with a bang. B